1. Field of the Invention
Embodiments of the present invention relate to methods of manufacturing a semiconductor package.
2. Description of the Related Art
The strong growth in demand for portable consumer electronics is driving the need for high-capacity storage devices. Non-volatile semiconductor memory devices, such as flash memory storage cards, are becoming widely used to meet the ever-growing demands on digital information storage and exchange. Their portability, versatility and rugged design, along with their high reliability and large capacity, have made such memory devices ideal for use in a wide variety of electronic devices, including for example digital cameras, digital music players, video game consoles, PDAs and cellular telephones.
While a wide variety of packaging configurations are known, flash memory storage cards may in general be fabricated as system-in-a-package (SiP) or multichip modules (MCM), where a plurality of die are mounted on a substrate. The substrate may in general include a rigid base having a conductive layer etched on one or both sides. Electrical connections are formed between the die and the conductive layer(s), and the conductive layer(s) provide an electric lead structure for integration of the die into an electronic system. Once electrical connections between the die and substrate are made, the assembly is then typically encased in a molding compound in a transfer molding process to provide a protective package.
In view of the small form factor requirements, as well as the fact that flash memory cards need to be removable and not permanently attached to a printed circuit board, such cards are often built of a land grid array (LGA) package. In an LGA package, the semiconductor die are electrically connected to exposed contact fingers formed on a lower surface of the package. External electrical connection with other electronic components on a host printed circuit board (PCB) is accomplished by bringing the contact fingers into pressure contact with complementary electrical pads on the PCB. LGA packages are ideal for flash memory cards in that they have a smaller profile and lower inductance than pin grid array (PGA) and ball grid array (BGA) packages.
Semiconductor die are typically batch processed on a panel and then singulated into individual packages upon completion of the fabrication process. Several methods are known for singulating the semiconductor packages including, for example, sawing, water jet cutting, laser cutting, water guided laser cutting, dry media cutting and diamond coated wire cutting.
Once singulated, fabrication of the flash memory card may be completed by encasing a semiconductor package within a pair of lids. The lids protect the package, as well as cover contacts pads, such as test pads that are left exposed in the package through the molding to allow for electrical test and burn-in after the package has been completed. It is also known to provide only a single lid, on one side of the package, to protect the package and cover exposed contact pads.
The one or two lids are typically affixed to the package in an injection molding process. One difficulty in affixing single-sided lids is that the single-sided lid formed in the injection molding process does not adhere well to the outer surface of the molding compound of the package formed in the transfer molding process. One solution has been to form a card 20 as shown in prior art FIG. 1, including a semiconductor package 22 and a lid 24 which partially wraps around the opposite side of the package. The wrap around configuration disadvantageously increases the overall thickness of the finished semiconductor card.